#include "stdio.h"
main()
{	 	 	 	 	    	
   double term,pi;
   int i;

   pi=1; //2
   
   for(i=1;i<=100;i=i+2)  //4
   {	 	 	 	 	    	
       term=(double)(i+1)/i*(i+1)/(i+2);//4
       pi=pi*term;  //4
   }

   printf("pi=%f\n",pi*2);//2
}